Open Question: i made 2 excel(2007) sheets. in the first one i added a drop down list which contained names of students.?

i made 2 excel(2007) sheets. in the first one i added a drop down list which contained names of students. on the basis of the name selected i showed details(present in sheet 2) of the student in sheet 1 using VLOOKUP. it matched names. the problem is that if the students have the same name then for both, details of first student are shown. i have roll no. in the second sheet. i want to display names in the list n acc to the name selected i want to show the correct details.....plz help
i cant add any column in between...............only at the end..............its actually a pretty lengthy project......i added roll no. at the end bt dont knw hw to use a function which does everything like vlookup bt compares not the first coln bt any coln.....